1. Field of the Invention
The present invention relates to a connection structure for a branch pipe in a high-pressure fuel rail such as a high-pressure fuel manifold or a fuel block, and more particularly to a connection structure for a branch pipe in a high-pressure fuel rail serving to pass a fuel under a pressure exceeding 1,000 kgf/cm.sup.2 to an internal combustion diesel engine.
2. Description of the Prior Art
FIG. 10 is a front view including sectional portions showing a connection structure in a manifold as a conventional high-pressure fuel rail, wherein a through passage (10) is formed to serve to pass a high-pressure fuel through a main pipe (11) and a plurality of through holes (13) are fromed in the axial direction of the through passage (10) (FIG. 10 shows only one through hole (13)).
A branch pipe (14) is inserted in each of the through holes (13), and said branch pipe (14) and the main pipe (11) are fixed together at a joint (W) by means of soldering or welding so that the through passage (10) in the main pipe (11) communites with a flow path (12) in the branch pipe (14).
In the connection structure for said branch pipe in the conventional high-pressure fuel manifold, the union of the joint (W) or portions subject to heat in the vicinity of the joint (W) often suffers a separation because these portions are exposed to repeated application of an ultra-high fluid pressure exceeding 1,000 kgf/cm.sup.2 and to incessant exertion of vibrations generated by the diesel internal combustion engine, thus resulting in fuel scattering or leakage and the separation of the branch pipe (14).